Sensei's Secret
by Kamen Rider Dimension
Summary: Lysithea thought it was just another one of the eccentric professor's famous tea parties. Little did she realise, she would learn more about what made Byleth so strange, a secret that has haunted his entire life... (One-shot)


**Fire Emblem Three Houses has taken over my life temporarily. I think it has for a lot of people. I just really wanted to see what I could do with the characters because there are quite a few I would love to play around with and explore. Even Byleth alone has a lot of interesting implications you can mess with, let alone all of the students, so don't be surprised if more of these one shots appear. Anyway, let's go!**

* * *

Byleth let the soothing scent of brewing tea float through the area, the sweet aroma bringing a sigh out of the blue haired professor. Along with a fine selection of treats from Enbarr, Byleth knew he had the makings for a perfect tea party. All that was missing was…

"Hello Professor! Did you call me?" Lysithea called out, pink eyes quickly alight with joy when they fell upon the delectable spread sat waiting. "Oh, is it a special occasion or something?"

"No, not at all. I merely thought I would take the opportunity to indulge a little bit." Byleth clarified, gesturing for the student to take a seat opposite. "I find myself feeling somewhat lonely drinking by myself and I had a feeling you would appreciate this blend the most."

To be honest, Byleth found it somewhat overpowering for his tastes. Compared to many of the other teas that the Officer's Academy had to offer, the honeyed fruit blend was the sweetest available. It pushed the boundaries of what could be considered tea with the sheer amount of candied fruit it contained; it was a relatively childish tea that only those with a true sweet tooth could properly appreciate.

When the professor came across it, Lysithea had immediately come to mind. The white haired girl enjoyed sweets and sugar perhaps more than was healthy, happily partaking whenever they were offered. It was fortunate that she and Mercedes weren't placed in the same house, otherwise Lysithea would practically be begging her to bake at every opportunity.

His thoughts were only made more apparent when Lysithea make a request that Byleth couldn't believe. Having taken a sip of the honeyed fruit blend and savouring its incredible sugar content, her eyes immediately began to scour the table before a gentle blush came over her cheeks.

"This is amazing Professor! I think it's going to become one of my favourite teas!" Lysithea praised. "But, um… do you have any sugar?"

He originally hadn't prepared any, for Byleth didn't believe that it was possible for someone to desire it with the tea. It was only the fact that it was for Lysithea that had the blue haired professor pulling out a small bowl of the substance, the smallest of smirks on his face going unnoticed by his student.

"So tell me. How are your classes coming along? I trust you aren't getting lost in the material." Byleth began.

One, two, three; the professor had to try his best to suppress his chuckles when Lysithea continued to put spoon after spoon of sugar into her drink. Said girl's blush grew when she caught sight of his amused look, quickly placing the spoon down after a stir.

"O-of course Professor! After all, we have you assisting us." Lysithea replied, a smile appearing on her lips as she drank. "You make lessons so involved, so entertaining while actually teaching us really important stuff – I swear I could fall asleep in some of Professor Von Esser's lectures. Even when we cover the stuff I already know, you make it seem like I'm learning something brand new."

"Well not all of the other students are so learned as you. It wouldn't be fair to have one student sitting without work while the others learn." Byleth said.

It had surprised Byleth when he had first come across it. Imagine his embarrassment after he had spent so much time formulating a proper lesson plan, only for Lysithea to politely raise her hand and tell him that she had already covered that level of material. If it weren't for his natural propensity for not showing emotion, then he would've broken down in embarrassment. He was lucky enough that he could come up with more advanced work on the spot.

"And I wouldn't want it any other way Professor!" came the cheerful reply, Lysithea pausing to pluck one of the cakes from the stand and take a bite. "Wow, these are delicious. I've only been able to have cakes from Enbarr when Edelgarde manages to get some imported. How did you manage to get them Professor?"

"My prior life has left me well connected." Was the vague answer, Lysithea glaring at Byleth before puffing out her cheeks in a huff; it didn't seem like he was going to elaborate. It wasn't as if anyone wasn't aware of Byleth's life as a mercenary, but apart from the fearsome reputation he and his father managed to earn, there was woefully little known about their professor. "Feel free to take as many as you like. I'm not particularly fond of them myself."

"You're not?" Lysithea asked. Well, she meant to, but her mouth was too occupied with half-chewed cake to properly formulate the words. Realising her mistake, Lysithea swallowed before continuing. "But there's nothing else on the tray. Didn't you prepare something for yourself?"

"There's no need. It's the job of a professor to put their students first after all." Came Byleth's casual dismissal. "Youth is not something to be wasted; we should all enjoy it to the fullest while it still lasts."

They were no empty words. Ever since he had been privileged enough to be gifted the position of professor at the Officer's Academy, Byleth had tried to do his best for the sake of his students. Whether it be sharing meals, learning hymns, fishing or overseeing tournaments, he had tried to ensure that everyone was as involved in school life as possible.

Even Bernadetta had been unable to avoid his efforts in the end. While it had taken a few misleading statements and more physical labour than the blue haired man would like to admit, the incredibly shy girl was starting to break out of her shell. Considering the small snippets of her upbringing he had been able to squeeze out of Bernadetta, Byleth was proud of what he had managed to achieve.

"I suppose you're right. But don't forget to treat yourself too Professor. You're always working so hard for the sake of everyone, but you never seem to take the time to just relax by yourself." Lysithea warned, receiving a shrug in return.

"I take time to relax. We're drinking tea, aren't we?" Byleth retorted gently, taking a sip for good measure. It did little to deter the look that Lysithea gave him.

"Yes, the tea that you chose for _me_. Alongside the cakes you chose for _me_." Lysithea returned, holding up her hand before the professor could continue. "Your tea parties are renowned throughout the monastery, you know? No matter who you're seen having tea with, it always seems to be tailored to their particular tastes. _Their _tastes, never your own. You say you relax, but it's an excuse for you to keep working. Nearly everybody's had tea or dined with you, but nobody knows what _you_ like to eat, what _you_ like to do as a hobby – because you never take time to do things for yourself. Isn't that weird to you Professor?"

"I am a simple man. I don't particularly have anything I favour, so might as well let the others have what they enjoy." Byleth tried to excuse, only to find Lysithea's face suddenly flinching away. The blue haired professor wasn't sure what he had done wrong, but he knew one thing for certain; he wanted to keep Lysithea from ever making that pained expression again. "Is there something wrong with that?"

"Professor… this isn't like when you first started teaching us. We've been through too much together." Lysithea spoke, far gentler than before as she looked deeply into Byleth's eyes. "You're doing that thing again, when you tell us white lies and hope we drop the topic. After everything you've helped me through professor, let me help you for once. Tell me the truth."

A conflicted visage fell upon Byleth's face. It wasn't overtly obvious, but to those who had gotten used to the blue haired man's usual stoic mannerisms, it was almost glaringly obvious. Thank goodness there were no others in the small garden, or there would be more questions that Byleth would've liked.

"…No, it's the truth. Just… underplayed, to say the least." Byleth eventually replied, his grip around his cup so hard that a fraction more power would have the delicate china shatter. "What I'm about to tell you must not reach the ears of any other, do you understand?"

"Professor. I trust you enough that I've told you everything about me. All of the pain, the suffering and torture I have been through to reach this point. Now it's your turn to trust me." Came the resolute answer, a fire coming to Lysithea's eyes.

Byleth took a deep breath. If there was anyone that he was going to tell this, it might as well be Lysithea; save for his father and perhaps Alois, she was the closest associate that the professor had at the Officer's Academy. A series of private tutorials, chance encounters and revelations meant that Lysithea was far closer to him than any other student.

It didn't mean he couldn't struggle with his words, moments passing in silence as Byleth was lost deep in thought. If it worried Lysithea, it didn't show on her face, a reassuring smile that spoke of maturity belying her youth.

"…Tell me, what do you taste when you bite into one of these?" Byleth asked, plucking another of the cakes from the stand and admiring it for a moment.

The question through Lysithea off guard, blinking owlishly before forming an answer.

"Well, there's some orange. Lots of sugar – I know, probably too much sugar. Um… just a really nice cake." The white haired girl replied, tilting her heads slightly in confusion.

Byleth didn't continue at first, for he placed the cake into his mouth, chewing it elegantly and daintily. For all of the times that the professor came off as crude, strange or odd thanks to the mercenary upbringing Byleth had experienced, there were the occasional moment when he seemed to hold far more class than even the practiced nobles. His etiquette when it came to food was one of those.

"All I taste is ash. I can say the same for any food. This tea, and any tea, tastes like mud water."

* * *

Lysithea didn't know how to react to such a statement. It sounded so outlandish, yet the tone Byleth spoke in meant that he was one hundred percent serious. The man rarely made jokes in the first place, so the chance that he would suddenly decide to do so at such an inappropriate timing… it was near impossible.

"I'm not like other people, even other mercenaries. I've never experienced the same joys that everyone else can." Byleth explained when it was clear that Lysithea wasn't able to respond. "I've lived my life pretty much like a zombie. I never felt much in the way of emotion, all food tastes horrible and if it weren't for my father, I would probably have died years ago simply because I didn't see the reason for living. It wasn't even something you could call depression – just sheer apathy to the world."

"…So the reason you never seemed to smile…"

"Yes. Was because I didn't even know how to."

The discovery was horrifying, yet the evidence was right in front of Lysithea. You would expect such an admission to hold some sort of undertone – fear, sadness, anger – anything. The way Byleth spoke however, it was as if they were discussing the weather.

"My father tried his best to hide his discomfort and help me. The mercenaries were incredible people, some of the brightest and most energetic friendly people you'll ever meet; he hoped they would rub off on me." Byleth continued, his eyes falling closed as familiar images passed before his mind. "It didn't work. I had a purpose in life – to become as strong as the mercenaries around me – but I still couldn't share in the happiness, or anger, or sadness that the people around me were feeling. I just became known as the stoic mercenary."

"S-so you've just been pretending all of this time? Every time you seemed to be amused, or disappointed in someone, it's all been a lie?" Lysithea asked, unable to keep the hurt from entering her voice. There was one thing echoing in her mind that she simply couldn't believe. "Every time you said you were pleased by my work, were those empty words?"

It didn't take long for Byleth to realise the issue. After all, it was something that Lysithea had been so pleased by when the professor had said it during one of their private tutoring sessions.

Lysithea had been a natural prodigy. Thanks to the horrors of her childhood, the white haired girl was gifted with a magical ability beyond any her age, allowing her to excel in the mystic arts and even qualify for the Officer's Academy at the tender age of fifteen. Anyone who came across her said that she had a knack for magic.

But it had only been Byleth who had praised her for the effort she put in, rather than the power she tried not to rely upon. He had been pleased with her work ethic and had said as such out of the blue one day. Those words had kept a smile on Lysithea's face through the night and a large majority of the day afterwards.

To think that they had been false… it was a thought more horrible than Lysithea could bear.

"No. I was telling the truth." Byleth replied, his face growing pensive. "And it's exactly because of people like you."

Now that got Lysithea's attention, the pain bubbling beneath the surface abating to give way to confusion once more. Neither of them realised that their tea had gone cold during the conversation, too lost in the conversation as Byleth gave a small nod of his head.

"People like me?" Lysithea parroted.

"I was woefully unprepared to be a professor here at the monastery, but I went along with it because the Lady Rhea ordered me to do so. I thought it was just another assignment and treated it as such." Byleth said. "I'm sure you can remember those days. I heard people call me strict, straight forward, demanding too much of students. I simply didn't care because I couldn't care. I had a mission to complete."

"But then I started interacting with the students and I suddenly _felt_ something. It took me a while to realise it, but seeing you and the others enjoying themselves, growing and becoming friends, it finally made me feel the emotions I've never had before. When I made others happy, it made me feel happy. When my students were sad, it made me feel sad. It was like somebody had turned the lights on – and I didn't want the lights to turn off. That's why I enjoy holding tea parties, singing and eating with everyone. I'm leaching off their emotions so I can feel them too. That's why I said I was proud of your efforts: because you showed me what it was like to feel pride."

"I… Professor…" Lysithea stumbled over her words, nearly spilling her tea in the process.

When the white haired girl rose a finger to her eyes, she realised that she had started to cry, quickly wiping the offending tear away. Who wouldn't feel bad for the professor after hearing a tale like that? The professor who they had called eccentric, joked about both behind his back and to his face, who had seemingly taken it all with a momentary smirk before continuing with his class…

Now she felt guilty for trying to force him away from what gave him joy in life. If this was what helped made him feel alive, if this changed his life for the better, then who was Lysithea to try and stop him from doing it?

"Owl, do you think differently of me now? Now that you understand how much of a leech I am." Byleth's question drew Lysithea out of her silence, eyes widening as she made to slam her hands on the table.

"No! You're not a leech! You're still the same Professor who's been so kind to us and taught us so much!" Lysithea objected, perhaps a little louder than she would've liked. Still, not even the use of the nickname he had given her, the nickname that used to irk her so, was enough to change her mind. "You're still the professor who finally praised me for me, rather than something I had forcibly implanted in me. If being around us makes you happy, then I would be a monster for taking that away from you."

"…Thank you..." Byleth said, releasing a breath he hadn't realised he had been holding in.

Suddenly, it felt as if there was a weight off his shoulders. Sure, it wasn't as if there wasn't _anyone_ else who didn't know about him, but it was the first time Byleth actually explained it to someone. The prospect that a student might learn by accident and break it to the monastery, incredibly slim and impossible as it was, had terrified Byleth, or at least, made him feel what he was pretty sure was terror. This way, it was under his terms and with someone who he had become close to.

"Like I said Professor, you've done so much for us. If this was enough to counter all that you've done, then I'd be more of a monster than the people who worked on me." Lysithea answered, a hand coming to her heart along with a smile to her lips. "Besides, if us being around you makes you feel better, then it gives me an excuse to stay close to you. Not that I needed one…"

The last sentence was barely more than a whisper, Lysithea's face burning red at the implications, but it changed to a pout when it was clear Byleth had completely missed the prompt. Then again, she shouldn't have expected anything else; Dorothea and Professor Casagranda were far more overt in their flirting and it did little to affect Byleth.

"I'm glad. I suppose we'll just have to plan another tea party then." Byleth remarked, giving a small tut as he took a sip from his cup. "I fear this is too far gone and my fire magic leaves something to be desired, unless you wish the table cloth to be set alight."

The smile returned to Lysithea's face as she gave a small wave of her finger, a gentle flame surrounding the tea pot and their individual cups, a feat that quite a few of the monastery's official mages would struggle to achieve.

"Ah. That works too."

"Don't worry Professor. Leave everything to me. If we can help make you feel, then we can help find something you can enjoy eating as well!" Lysithea declared with a clap of her hands and an impish glint to her eyes. "I'm sure if we keep trying we'll find something you like."

"Maybe you can."

Byleth let a small chuckle out, something that he would never have been able to do before he arrived at the monastery. It seemed that yet again, Lysithea had become determined and would no doubt give her all to find some sort of miracle that even he would never have thought off.

He truly was proud of her.

* * *

**Real talk, Lysithea needs all of the hugs and head pats. **

**Anyway, I really like how they managed to integrate a silent character so well into the story. Byleth's not just silent for the sake of player ****immersion, there are actual story implications for why he doesn't emote or speak very often. They've also done something like this with the breath of the wild Link and why he doesn't speak or emote much. It's nice to see Nintendo doing that.**

**So please review and tell me what you think and perhaps look forward to more of these in the future! probably the very close future.**


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